1. Field of the Invention
The invention relates generally to components of an electrical circuit such as those used with a vehicle horn. More specifically, the invention related to an electrical contact with improved wear and operating life characteristics.
2. Background Art
Horns are used in all types of vehicles. A horn is particularly important in a forklift truck because of the significant dangers surrounding the use of forklift trucks. For example, many forklift trucks have structures that obscure the driver's view, making it difficult for the driver to see pedestrians in the path of the forklift truck. In addition, many forklift trucks are operated in a warehouse, where a pedestrian could walk around a blind corner and into the path of a forklift truck. In such a case, neither the pedestrian nor the forklift truck operator is able to see the other in time to prevent an accident. Additionally, forklift trucks are often used to carry heavy loads that could fall and cause severe injuries in an accident.
A horn is an important safety device on a forklift truck because it enables the operator to warn people nearby to stay clear of the forklift truck. Because of the important safety aspects, the horn in a forklift truck is used much more often than a horn in a typical passenger car. In many cases, the horn on a forklift truck is used more than one million times during the life of the forklift truck.
Most vehicle horns, including horns on forklift trucks, are activated by depressing the center of a steering wheel. When the center section of the steering wheel is depressed, it makes electrical contact to complete the horn circuit. The primary difficulty in completing a horn circuit is that it must be done in a way that will still enable the rotation of the steering wheel to steer the vehicle.
FIG. 1 shows a steering wheel assembly 100 that includes a steering wheel 101 connected to a steering column 105. The steering column 105 connects to the steering wheel 101 just above a base or a control assembly 107. The steering wheel 101 includes a center section 104 that may be depressed to energize a horn circuit (not shown).
FIG. 2 is an view of the underside of the steering wheel 101. The steering wheel 101 includes a socket 204 for connecting to a steering column (e.g., column 105 in FIG. 1). The steering wheel 101 also includes a conductive portion 202. In some embodiments, the conductive portion 202 is attached to the underside of the steering wheel 101, and in other embodiments, the conductive portion 202 may be integral to the steering wheel 101.
FIG. 3 is a cross section of a steering wheel 101 with a conductive portion 202 located on the underside of the steering wheel 101. The steering wheel 101 is connected to a steering column 105. A control assembly 107 is positioned below the steering wheel 101. A conductive prong 301 extends from the control assembly 107, and the prong 301 is coupled to the control assembly 107 (e.g., with bolt 308 or other suitable means). The prong 301 extends to be in electrical contact with the conductive portion 202 on the steering wheel 101. As the steering wheel 101 rotates during the steering of the forklift truck (not shown), the prong 301 maintains electrical contact with the conductive portion 202.
In some embodiments, the conductive portion 202 is electrically connected to the center section 104 of the steering wheel 101. When the center section 104 is depressed, the circuit is closed, and an electrical connection is created between the conductive portion 202 and the steering column 105, by way of the center section 104 of the steering wheel 101. The base of the prong 301 is electrically connected to the horn circuit, and the steering column 105 is electrically connected to ground. Thus, by depressing the center section 104 of the steering wheel 101, the horn circuit is closed, and the horn will sound.
In the embodiment shown in FIG. 3, the prong 301 includes a protrusion 305 at the end of the prong 301 for making electrical contact with the conductive portion 202 of the steering wheel 101. It is noted that different shapes and geometries on the end of a prong may be used. The shape of the contact point on the prong in not important to the operation of the circuit.
Wear-induced horn failure is considered a normal limitation of a horn circuit lifespan and a worn contact is often the cause. Although the prior art approach of replacing, or providing an extension for, a worn prong or brush head is effective in most cases, in certain applications even short-lived vehicular horn failure may pose an unacceptably high safety hazard.
What is still needed, thus, is a horn circuit having a reduced risk of wear-induced failure.